Wireless Sensor Monitors Pressure During Endovascular Repair

Placement of a wireless pressure sensor during endovascular repair (EVAR) of an abdominal aortic aneurysm is effective in monitoring pulse pressure in the aneurysmal sac, according to results of a new study.

Researchers at the Jikei University School of Medicine (Tokyo, Japan) conducted the acute pressure measurement to confirm an aneurysm sac exclusion (APEX) clinical trial that included 76 patients at 12 sites. The aneurysms were being treated with a bifurcated, modular, endovascular stent graft, and most of the procedures were performed via bilateral femoral cutdowns. An EndoSure sensor was inserted into the aneurysm before the endograft, and pressure was measured at different steps of the repair procedure. The mean estimated blood loss during the aneurysm repairs was 471 ml, and operative time averaged 205 minutes.

At the end of the procedure, pressure in the sealed-off aneurysmal sac decreased by 46%, denoting operative success. The investigators observed close agreement between pressure measured by the EndoSure sensor and angiography. The sensitivity for detecting endoleaks, indicating the incomplete exclusion from the main circulation, was 93.9% and specificity was 80%. During the next 30 days, there were no adverse events attributed to the sensor and no evidence of device migration. At 30-day follow-up, sensor signal was detected in 97% of patients. The study was reported in the February 2007 issue of the Journal of Vascular Surgery.

"Implantation of the wireless pressure sensor is safe, and remote aneurysm sac pressure sensing is feasible. It was a valuable guide in evaluating the completeness of the EVAR procedure. Long-term study will be needed to prove its efficacy for postoperative surveillance,” concluded lead author Dr. Takao Ohki and colleagues.

The EndoSure sensor is a product of CardioMEMS (Atlanta, GA, USA). The 30 x 5 x 1.5 mm sensor contains no battery and is powered externally by a radio-frequency (RF) generator. The sensors are extremely stable, operate over the full physiologic range of pressures, and have a resolution of 1 mm Hg. A change in pressure alters the resonant frequency of the sensor, which is monitored by an antenna placed on the patient's abdomen.



Related Links:
Jikei University School of Medicine
CardioMEMS